Method for treating ferruginous waters.



L. S. HUGHES.

METHOD FOR TREATING FERRUGINOUS WATERS.

APPLICATION FILED OCT. 2, 1913.

m a w a W we I masses.

' LOUIS S. HUGHES, OF CHICAGO, ILLINOIS.

lllEIEl'll'HOID FOR TREATING FERRUGINOUS WATER S.

Application filed ctober-2, 1913. Serial No. 792,960.

To all whom it may concern:

-Be it known that T, LOUIS S. HUoHEs a .j citizen of the United States, residing at oincago, in the county of Cook and State of Illinois, have invented certain new and use ful Improvements in Methods forTreating .FBII'IIgIDOUS Waters, as set forth in the following specification.

, Myinvention relates to the method of treating mine water and more particularly to the treatment of acid ferrugi'nous water of .the type frequently obtained in the operation of coal mines. The invention has-for its object broadly to-purify these waters by removing the acid and astringent ingredients therefrom and to recover from the mine water merchantable by-products.- The constituents of this Water, which are actively inj urio'us to health and which must be removed to prevent contamination of streams, ponds and the like, are free sulfuricacid and sulfates of iron and alumina.

While my invention is herein described in'connection with mine water, it may, of course, be practised efiectively in the treating of water from other sources without departing from the spirit and scope thereof. The term neutralization used in describing my invention refers not only to the reactions with the free acid but alsoto reactions with the acid equivalents of the compounds present which'are subject to decomposition by alkalis and which give an acid reaction, it being necessary in the treatment of the water that these latter substances, as

. well as the free acid be neutralized. Because of the very large volume of the water to be treated and the large amount of dissolved by-products through the use of cheap mate-' rial and with a provision of simple and ins S salts carried thereby, the use of the ordinary water softening chemicals such as'.caustic soda and soda ash is inhibited because of their cost.

A principal object of the invention is to provide a process which will purify the mine water and the like and makev possible the collection and treatment of'merchantable expensive apparatus.

A further object of the invention is. to

provide a process of treating mine water and the like which may be carried on without waste and without appreciable diminution of the material provided for the pur pose. I

A still further object of the inventionis to recover fromth'e mine water various prodtrating a preferred form of apparatus to be used in the practice of my present invention.

On the drawing,

Specification-0f Letters Patent. Patented Nov. @X, 191% Figure 1 is a vertical central section of an apparatus which may conveniently be used in carrying out the method embodying my invention, and

' Fig. 2 is a top plan view of the same.

The mine water as it flows or is pumped from the mine is preferably first passed over a large quantity of a raw carbonate of an alkali earth, limestone'being preferabl employed, the pieces of limestone being of relatively large size to permit the mine water to ass over, between and around the pieces. uring this passage over the limestone the neutralization of the mine Water proceeds through three stages: First, the free'acid is neutralized; second, a suspended colloidal precipitate is formed which shows no tendency to settle, and third, when the neutraliv the neutralization of the free acid itself is complete the limestone acts chiefly as a catalytic agent. The settling of. the precipitate should be delayed until after the limestone is passed and to this end I increase the velocity of the water over the limestone toward the end of its passage. This may be done in any of a number of simple ways, as for instance the limestone ma be deposited in the bottom of a number 0 long troughsand the water led successively therethrough, the cross-sectional area of the troughs through which the water last passes being materially less than the cross-sectional area of the troughs into which it is first admitted. uch an arrangement of troughs is shown on the drawing. A pipe 3 leading from the mine opens into a wide trough 4 in which ice is disposed a quantity of finely broken limestone 5. The pipe 3 enters the trough near its top and the water being delivered from the pipe falls between the adjacent wall 6 and a baffle-plate 7 perforated at its bottom as at 8. to cause the water to pass about the limestone from the bottom. From this trough the water is conveyed by a pipe 9 to a second trough 10 of less width than the trough 4 and containing pieces of limestone coarser than those in the trough 4. The pipe 9 connects with each of the troughs 4 and 10 adjacent to their top edges. A bafileplate 21 similar in all respects to the baffleplate 7- is provided in the trough 10 and causes the mine water to flow from the bottom of the trough through the limestone. From the trough 10 the mine water is conveyed to a third trough 11 by a pipe 12, this .trough being of less width than the trough 10 and containing pieces of limestone 13 larger than those in the trough 10. A baflleplate 14 similar to the battle plates 7 and 21 and similarly placed causes the mine water to come in contact with the limestone near the bottom of the trough. These troughs are placed at different levels, the first and widest one 6 being at the highest and the last and smallest one 11 being at the lowest level.' Although three troughs are shown on the drawing it will be readily appreciated that any number may be employed. The reduced sectional area causes an increased rate of flow per unit area and consequently delays the settling of the precipitate and delays also the incrustation of the limestone materially, although, of course, the limestone will in time become coated and will need to be replaced or cleaned. A proper sizing of the stone and adjustment of the rate of flow will render this replacement or cleaning only occasionally necessary.

After passing the limestone the mine water may, it thought desirable, be subjected to the action of some alkali such as quick or slaked lime, the action of the limestone, however, as it has already neutralized the free acid and formed the precipitate to be deposited, requiresthat very little quick or slaked lime be added. If it is desired to hasten the precipitate still more a natural alkaline water may be introduced or it may be used instead of the lime treatment just described. If conditions are. such that the gripe water may be conducted through sufiicientv troughs containing limestone both the alkaline water and the lime will be found unnecessary.

After the water has been entirely or sub-' stantially entirely neutralized I cause it to be violently agitated. This agitation can be easily accomplished by passing it down a steep incline on which are placed obstructions to cause splashing of the Water. The agitation causes the precipitate to coagulate and to be readily deposited when the velocity of the water is reduced. This agitation maybe produced in a number of ways, the incline shown on the drawing consisting of a trough15 narrowing toward its outlet high rate of velocity at which the water is thus conducted carries the greater part of the precipitate, which at this point of the treatment. is ready to rapidly settle, well in toward the center of the vat. The precipitate drops to the bottom of the vat so rapidly that water may be conducted continuously therethrough, it only being necessary that the vat be sufficiently large to permit the .water to remain in substantially a quietstate for an instant.

A suitable form of vat is shown on the drawing. This consists of a metal tank 17 of frusto-conical shape, the bottom of the vat 18 being smaller than its top. The trough 15 extends into this tangentially so that the water whirls somewhat about the center during the settling of the precipitate. The outlet 19 is relatively larger than the inlet and the water flows out from the .vat at low velocity. t

The precipitate is removed from the vat, preferably by a suitable suction pump (not shown) through a pipe 20 extending nearly to the bottom of the vat, and delivered into a filter press where it is squeezed into compact cakes driving out-much of the free water. The remaining water may be driven out, if desired, by blowing compressed air through the press after it is filled with the precipitate. Other means for collecting the precipitate may be employed, of course, and I do not wish to be limited to the use of any particular means for this'purpose. The pressed cake thus provided may be used in the purification of gas or it may be converted into aint pigment. If the cake is roasted at a 0w, heat in a reverberatory furnace a Venetian red pigment of fine quality is produced. In connection with the foregoing it is to be understood that as the mine water passes through the successive bodies of the limestone its movement not only will be accelerated by reason of the decreasing crosssectional area of each of the troughs, but as the broken pieces of the limestone in each trough are larger than those in the imme diately preceding trough the interstices between the pieces of each body are relatively larger than the interstices between the'pieces of the preceding body. This reduces the frictional impedance to the passage of the water and tends to increase the velocity of water and the its flow. Furthermore,

precipitate through the trough 15 the incidental agitation causes the particles of the precipitate, which up to this point are held in suspensibn, to imy, pinge upon and adhere to each other, the

mass of the adhered ficient under this coagulation to quickly settle when the water enters the vat. Thus the precipitate accumulates in the vat and may be removed readily therefrom in the manner reviously described. 7

It will be apparent, therefore, that mine water treated in accordance with my present invention may be cheaply purified through the provision of simple and'inexpensive apparatus and that a valuable product will be I obtained which may be used for the purification of gas, the manufacture of a aint pigment and for other purposes. T e process s susceptible of numerous modificat'ons and scope of sacrlfic ng any of its mavelocity.

. 3. The process of treating mine water, which consists in first pass'ng the same over in the passage of the particles becoming sufvelocity. M

its steps may be varied in many ways with out vdeparting from the spirit or water, which consists "the velocity relatively small pieces of a raw alkali earth,

and subsequently over relatively larger pieces thereof. i. The process of treating mine water,

which consists in first passing the same over relatively small pieces of a raw alkali earth, and subsequently passing said water over relatively larger pieces thereof at a higher 5. The process of treating ferruginous water, which consists in subjecting the same 1n successive stages to the action of separated bodies of anagent possessingalkaline characteristics, whereby to neutralize the 'free acid contained in the water and toproduce a suspended precipitate, saidbodies being arranged in relation to each other to ofi'er decreased resistance to the passage of the suspended precipitate as the latteradvances through the successive stages of treatment, and then coagulating the suspended precipitate to effect sedimentatlon thereof.

6. The process of treating ferrugmous 1n.successive stages rated bodies of 'an agent possessing alkaline characteristics, whereby to neutralize the free acid contained in the water and to proin subjecting the same, to the action of sepaduce a suspended precipitate, accelerating of flow of the water in its transit through the successive stages of treatment, whereby to hold the precipitate in suspension, and then coagulating the suspended precipitate to eflect sedimentation.

, LOUIS S. HUGHES. Witnesses: 'J. C. Canrnm'sn,

FRANKLIN M. WARDEN. 

